Thread grinding machine



July 4, 1950 F. TURRETTINI 2,513,694

THREAD GRINDING MACHINE Filed Dec. 18, 1947 4 Sheets-Sheet 1 July 4, 1950 F. TURRETTINI THREAD GRINDING MACHINE 4 Sheets-Sheet 2 Filed Dec. 18, 1947 4 Sheets- Sheet 3 in 1 6/7/0r fW/Mnd 677977/ 5/ July 4, 1950 F. TURRETTINI THREAD GRINDING MACHINE Filed Dec. 18, 1947 July 4, 1950 F. TURRETTINI 2, 3,6

THREAD GRINDING MACHINE Filed Dec. 18, 1947 4 Sheets-Sheet 4 FE RNA No Tm R E rmu 67 6 XL 01 w J INT-T01? -27 Patented July 4, 1950 THREAD GRINDING MACHINE Fernand Turrettini, Bellevue-Geneva, Switzerland, assignor to Societe Genevoise dInsti-uments de Physique, Geneva,

Switzerland, a

Application December 18, 1947, Serial No. 792,436 In Switzerland November 22, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires November 22, 1963 Thread grinding machines for grinding circular grooves located within equidistant parallel planes are already known. This kind of work is currently carried out when tools such as screw thread cutting tools or milling cutters for milling screw threads and gears, or profiled cutting tools with which the jaws of snap gauges intended for checking up screw threads are provided, are to be manufactured.

Up to now, for carrying out this work, the lead-screw was disengaged from the work spindle and it was revolved in a discontinuous way by hand; or, a slight displacement was transmitted to the nut of the lead-screw, by means of a hand operated element, and said displacement was then transmitted both to the lead screw and to the table.

There is, however, an inconvenience in the now mentioned methods, which is the lack of accuracy. In fact, the operator can make a slight error in the successive settings of the position of the table with respectto the position of the grinding wheel. Moreover, the materially unavoidable play of the control elements must, at all events, be takenup before the table starts its setting motion.

An object of the present invention is to provide novel and simple means for eliminating the above mentioned drawback; According to an important feature of the invention, the work spindle causing the rotation of the work-piece, drives a lead screw which, in turn, produces the displacement of the table carrying both the work spindle and the work piece.

One of the several possible'forms'of execution which can be given to the present invention and which merely intends to give a more substantial idea of the features embodied in it, com-prises a double motion transmission device from the work spindle to the lead-screw, the one 'of 'which shows an intermittent action and includes a friction clutch dependingfrom'a stop member, whereas comprises a= permanent gearing" the other one connection.

Moreover, a control device is provided'allowingthe friction clutch to enter: into actionintermittingly, for moving-the table forward by a length" corresponding'to one revolution of the work spin-' dle and by a control member, wallowing either-'01 i the transmission devices-to be used, with a view to grind either grooves located in parallel planes:

4 Claims. (01. 51-232) In the attached drawing:

Fig. 1 is a sectional partial longitudinal sectional lay-out.

The Figs. 2, 3 and 4 are cross sections through IIII, III'III and. IVIV of Fig. 1, respectively Fig. 5 shows certain details in perspective' Y Fig. 6 is a general view in elevation.

Fig. 7 is a view in profile. I

The thread grinding machine represented coin-- prises a sliding table 6a carrying a steady headstock 6, in which the spindle l revolves, and, in front thereof, a centre (see Fig. 6). The workpiece to be ground 56 is located between the spindle and the centre, and is set into' rotation by the driving plate 35 of spindle I, the latter being itself driven by a motor 51, by the inter mediary of the pinions 32 and 33 and of a changespeed 58 (see Fig. 7 The table displaces itself in front of the grinding wheel 59 (see Fig. 6), mounted on the bed 44, owing to the lead screw I4 revolving within a nut I5 fixedonto this bed. The rotation of the lead-screw I4 is brought about by the spindle l which is connected to that screw by means of a mechanism inserted between'the spindle and a shaft 8 and, starting from this latter, by means of a usual gear train 9, H], II and I3, which train is changed when one wishes to modify the travel which the table performs for one revolution of the spindle.

The hereabove mentioned mechanism comprises a shaft 30 parallel to the spindle I as well as to the shaft 8 and inserted between both these members. This shaft revolves in the head-stock means'of a key 180, a, pinion 5 provided with a circular groove 5| '(see Fig, 4), in which engages a' finger 52 secured to a shaft 53 rotatably sup:,, ported in the casing and manually operable byf a handle 54. Upon operation of this latter, the

sliding sleeve l8, which is shown in its neutral positionin Fig. 1, will be displaced, either towards the right or towards the left. Pinion 5 is con- 'stantly in mesh with a pinion! fixed on the shaft 8, and, when the sliding'sleeve is shifted towards the left, thispinion' 5 comes in mesh with a pinion 3 secured to'the work spindle I. By the side of pinion 5 is mounted loose on' the sliding sleeve IS a pinion 4 which, when shifting the sleeve J towards the right, comes'in' mesh with a pinion 2 made integral with the above mentioned pinion 3. In this position the pinion 4 acts on a'friction clutch I2 comprising friction discs IZafas-"f tened by studs l2b to the pinion 4 and co-operating with friction discs I2c dependent in rotation upon sliding sleeve I 8. A sleeve 21, keyed at I2d on the sliding sleeve I8, is submitted to the action of.a-spring 28 whichpresting against "a part 29 fixed 'to the sliding sleeve, presses "the discs against each other. The pinions 2, 3, 4, and I show the same diameter.

At its opposite end, in Fig. 1, the sliding sleeve I8 shows a collar I8a on the periphery of which a single notch I8b is provided. At the left hand of this collar, there is a sleeve i9 provided with another collar I9 (see also Fig. 3) mounted loose on the sliding sleeve I8 and a disc 23 mounted loose on the sleeve l9. An elastic device:34, pushing the disc 23 against the stop piece 34a, f-astened up to the sliding sleeve, presses against the collar I811, the sleeve I9 which is also provided with a notch 22. This latter can align itself with the notch IBb; in the collar I8a a pin 2! is fixed, which engages in a groove in the shape of an arc of circle of the sleeve 'I:9,'whereby;said collar .is allowed to drive thissleeve with an angular displacement which varies whengthe rotation direction isxreversed. 0n the disc 2.3 are fixed two :stops 2.6a and 2612 .between whichpasses a stem .26, fixed on the casing.

On this latter aretaining pawl 4i, pivoted at Ma, is provided with a tooth .42 and a heel 38..

The tooth (Ii-is intended to engage in the notch I. 8b-when the notch .22 is in alignment therewith. "Whenthe tooth'42 is engaged into these notches, the heel'38'rests oneither of the teeth of a cam .39., This latter is fixed on a shaft 40 :to which is also fixe a ratchet wheel 4.3 wit which cooperates a pawl 4.9 pivoted onapin 50. This latter is fixed to aworm gear 48, in mesh with a helical p monA'I fixed-on asshaf 46. This shaft 46 is rotataloly supported inthe casing and manually operable by ,a handle 45 which can be displaced between two stops 45a. The hereabove mentioned mechanism comprising all of the referenced qpalts'starting from the 'collar I 8b, con-.-

stitutes the control device which allows operation of the friction-clutch.

The sliding sleeve l8 being located in the neutral position shown in Fig. fl, supposethat one wishes to grind a screw thread. By means of handle 54, the sliding sleeve I8 is shifted towards the left until the pinion 5, constantly in mesh.

with pinion comes in mesh with pinion3. From that.moment,the work spindle I is connected by the .gear train3, .5, 1, 9,), II and I3 .to the lead screw I4 and drives this latter in the usual way. The cone I'I provided on the ring I6 fixed to the collar Ifla, has placed itself underneath the pawl 41, Which. thus, iSinoperative.

Suppose, on the contrary, thatone wishes to ind equidistant circular grooves., One will shift towardsstharight by meansof the handle 54 the slidingsleeve Ill. One sees that the notches I. 8b and. 22 hichare aligned for one rotation direction only, willplace themselves und r -.-th t eth 42 of the pawl 4 I :th lpinion-4 comes in m sh :with the pinion 2;. .Thefriction clutch I2 is induced to only slide, the sliding sleeve I8 which it is intended-torevolve in the irection of e rr w 2 (Fie- 2) b ing just p evented by pawl 42 from. revolving; the lead-. screw remains therefore .idle whereasthe work sp ndle I revolves, .andconsequently .the,grindns wh l rinds a ular gr ove. When one wants t grind the next groove. the handle '45 is displaced un l it rests. a ainst the abutment 45a, opposite .to the onea-gainst which it had rested ustbefore, it b ing then returned to its "revolution until the pawl 4|, which, in the meantime, has been released by the tooth which did lift it, takes again its initial position into the notch I812; this revolution of the sliding sleeve I8 causes the table to advance the interval between two adjacent circular grooves. In the return motion of handle 45, this latter does not drive thecam 39,-owing to the pawl 45.

Suppose that after having performed a first grinding run ofthe circular grooves one wants to .return the table idle into its initial position, for performing a second run. It will then suffice to cause the work spindle I to rotate in the reverse direction, whereby the rotation direction of the lead-screw and, of course, of all intermediary members, \will' be changed over. During this return motion, if the sleeve-fitted with the collar I9 and the disc 23 (seeFi'g. 3) should not :exist, the pawl 4i would be lifted at each revolution :of the :slidingsleeve I18, and would then fall again, whereby :a disagreeable noise and an. unnecessary wear would be produced. The sleeve I9 and the disc 23 are provided to eliminate thisv inconvenience; to this end, the sleeve I9 is connected to thecollar 18a by a coupling provided with a play, the coupling member being the .pin 2 -I co-operating with the groove. 20, and the. :play

being limited-by the travelithis pinwmayzmake.

within the groove; the sleeve .I-Qis constantly braked its rotation by the disc 23 which can only rotate through an {angle limited. by the stops 26b and 26a, thrusting against thexstem "26;; conseguentlyythe sleeve I9 always .lags,-whateverthe rotation direction may be, with respect to the collar'lBaandit can thustake two de-.

termined positions according to the rotation direction with respect 1301180" 1 In one of the rota-' tion directions, the relative positions of sleeve [9 and of collar I8a such that the notches 22 and I8?) arelocated-in.alignment with one another and that, consequently, the tooth 42 of the pawl 4i canstop the rotation of notch IBb. In the opposite rotation direction, notch .22 .is. angularly notch I8b-and theretainingpawl 4.I 'willagain' enter in operation I o I WhatI claim is: v

1.,In a thread grinding.machine, in' combinae tion a frame, -a:tablemovably mounted onsaid frame, a work spindle rotatably supported onsaid table, a lead-screwrotatably supported in said table and operatively engaging said frame to movesaid' table thereon, means forxrotating said work-spindle, first motion transmitting meansffor continuously driving said lead-screw from said work-spindle,isecondmotion transmitting means .for'intermittingly driving said leadscrew "from said work-spindle, said second mo tion'transmitting means comprising a friction coupling dependent upon a'stopmember, control means .actingon said friction coupling for rendering it operative intermittingly 'fonshifting .said table forward by a length corresponding to the rotation of the lead-screw produced by one revolution of said work-spindle, and manually operable means determining operative action of either said first or second motion transmitting means.

2. In a thread grinding machine, in combination a frame, a table movably mounted on said frame, a work-spindle rotatably supported in said table, a lead-screw rotatably supported in said table and operatively engaging said frame to move said table thereon, means for rotating said work-spindle, first motion transmitting means for continuously driving said lead-screw from said work-spindle, second motion transmitting means for intermittingly driving said leadscrew from said work-spindle, said first and second motion transmitting means comprising a common gear train and a common intermediate rotatable shaft, manually operable means determining operative action of either said first or second motion transmitting means, said manually operable means comprising a sliding sleeve mounted on said common intermediate shaft and dependent in rotation thereupon, said second motion transmitting means comprising a friction coupling mounted on said sliding sleeve and dependent on a stop member, and control means acting on said friction coupling for rendering it operative intermittingly for shifting said table forward by a length corresponding to the rotation of the lead-screw produced by one revolution of said work-spindle.

3. In a thread grinding machine, in combination a frame, a table movably mounted on said frame, a work-spindle rotatably supported in said table, a lead-screw rotatably supported in said table and operatively engaging said frame to move said table thereon, means for rotating said work spindle, first motion transmitting means for continuously driving said lead-screw from said work-spindle, second motion transmitting means for intermittingly driving said leadscrew from said work-spindle, said first and second motion transmitting means comprising a common gear train and a common intermediate 6 rotatable shaft, manually operable means determining operative action of either said first or second motion transmitting means, said manually operable means comprising a sliding sleeve mounted on said common intermediate shaft and dependent in rotation thereupon, said second motion transmitting means comprising a friction coupling mounted on said sliding sleeve, said sliding sleeve having a notch in which engages a retaining pawl for rendering said friction coupling operative in the rotation direction of said sliding sleeve corresponding to the return motion of said table, and means for momentarily disengaging said retaining pawl from said notch to render intermittingly inoperative said friction coupling in the rotation direction corresponding to the forward motion of said table.

4. In a thread grinding machine, the combination as claimed in claim 3, wherein an auxiliary sleeve having a notch is mounted on the sliding sleeve adjacent the notched part thereof and connected therewith by a coupling provided with an angular play in such a way that said auxiliary sleeve always lags, whatever the rotation direction may be With respect to said sliding sleeve, and is thus adapted to occupy two positions with respect to said sliding sleeve, namely a position corresponding to the idle run of the table in which both notches are angularly displaced with respect to each other, and a position corresponding to the forward motion of the table, in which both notches are in alignment, thus allowing the retaining pawl to engage thereinto.

FERNAND TURRE'ITINI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,634,386 Schramm et al July 5, 1927 2,349,477 Turrettini May 23, 1944 

